Longevity or Remaining Life Expectancy
How long from the present the item is expected to last under Archival storage conditions?
1 – Very Short: 1-5 years
2 – Short: 5-20 years
3 – Medium: 20-50 years
4 – Long: 50-100 years
5 – Very Long: 200 years
Very Short – compact disc recordable (CDR) 1-5 years
Longevity or Life expectancy is an important factor in considering what to preserve next. Passive preservation provided by storing the collection under the recommended archival storage conditions is a key preservation strategy.
However, if your testing is showing that loss of content is a risk for a particular format, no matter how well it is stored, that may become a factor in asking for more resources for purchase of equipment or beginning a new preservation project based on that format. An example would be CDRs and DAT tapes, where we may be at risk of losing some content from these formats in the near future. On the other hand, Shellac discs are considered to have a long life expectancy.
Being aware of factors influencing longevity are important, so testing for vinegar syndrome of film sound magnetic soundtracks and targeting particular tape stocks and brands that are known to deteriorate faster than others become important strategies in pinpointing possible material to be preserved under your preservation projects.